EP3274400B1 - Polyéthylène à ultra haut poids moléculaire stabilisé à l'état fondu - Google Patents

Polyéthylène à ultra haut poids moléculaire stabilisé à l'état fondu Download PDF

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Publication number
EP3274400B1
EP3274400B1 EP16716966.3A EP16716966A EP3274400B1 EP 3274400 B1 EP3274400 B1 EP 3274400B1 EP 16716966 A EP16716966 A EP 16716966A EP 3274400 B1 EP3274400 B1 EP 3274400B1
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antioxidant
solid material
uhmwpe
cio
melt
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German (de)
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EP3274400A1 (fr
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Dirk Pletcher
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Zimmer Inc
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Zimmer Inc
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
    • C08J7/04—Coating
    • C08J7/06—Coating with compositions not containing macromolecular substances
    • C08J7/065—Low-molecular-weight organic substances, e.g. absorption of additives in the surface of the article
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
    • C08J7/12—Chemical modification
    • C08J7/123—Treatment by wave energy or particle radiation
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L27/00—Materials for grafts or prostheses or for coating grafts or prostheses
    • A61L27/14—Macromolecular materials
    • A61L27/16—Macromolecular materials obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L27/00—Materials for grafts or prostheses or for coating grafts or prostheses
    • A61L27/50—Materials characterised by their function or physical properties, e.g. injectable or lubricating compositions, shape-memory materials, surface modified materials
    • A61L27/505—Stabilizers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
    • B05D3/06—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by exposure to radiation
    • B05D3/068—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by exposure to radiation using ionising radiations (gamma, X, electrons)
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C71/00—After-treatment of articles without altering their shape; Apparatus therefor
    • B29C71/02—Thermal after-treatment
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C71/00—After-treatment of articles without altering their shape; Apparatus therefor
    • B29C71/04—After-treatment of articles without altering their shape; Apparatus therefor by wave energy or particle radiation, e.g. for curing or vulcanising preformed articles
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J3/00—Processes of treating or compounding macromolecular substances
    • C08J3/20—Compounding polymers with additives, e.g. colouring
    • C08J3/203—Solid polymers with solid and/or liquid additives
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J3/00—Processes of treating or compounding macromolecular substances
    • C08J3/24—Crosslinking, e.g. vulcanising, of macromolecules
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J3/00—Processes of treating or compounding macromolecular substances
    • C08J3/28—Treatment by wave energy or particle radiation
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
    • C08J7/08—Heat treatment
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00—Use of organic ingredients
    • C08K5/0008—Organic ingredients according to more than one of the "one dot" groups of C08K5/01 - C08K5/59
    • C08K5/005—Stabilisers against oxidation, heat, light, ozone
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00—Use of organic ingredients
    • C08K5/04—Oxygen-containing compounds
    • C08K5/15—Heterocyclic compounds having oxygen in the ring
    • C08K5/151—Heterocyclic compounds having oxygen in the ring having one oxygen atom in the ring
    • C08K5/1545—Six-membered rings
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00—Use of organic ingredients
    • C08K5/49—Phosphorus-containing compounds
    • C08K5/51—Phosphorus bound to oxygen
    • C08K5/52—Phosphorus bound to oxygen only
    • C08K5/529—Esters containing heterocyclic rings not representing cyclic esters of phosphoric or phosphorous acids
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L2430/00—Materials or treatment for tissue regeneration
    • A61L2430/02—Materials or treatment for tissue regeneration for reconstruction of bones; weight-bearing implants
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C35/00—Heating, cooling or curing, e.g. crosslinking or vulcanising; Apparatus therefor
    • B29C35/02—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould
    • B29C35/08—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould by wave energy or particle radiation
    • B29C35/0866—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould by wave energy or particle radiation using particle radiation
    • B29C2035/0877—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould by wave energy or particle radiation using particle radiation using electron radiation, e.g. beta-rays
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2023/00—Use of polyalkenes or derivatives thereof as moulding material
    • B29K2023/04—Polymers of ethylene
    • B29K2023/06—PE, i.e. polyethylene
    • B29K2023/0658—PE, i.e. polyethylene characterised by its molecular weight
    • B29K2023/0683—UHMWPE, i.e. ultra high molecular weight polyethylene
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2323/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
    • C08J2323/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
    • C08J2323/04—Homopolymers or copolymers of ethene
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2323/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
    • C08J2323/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
    • C08J2323/04—Homopolymers or copolymers of ethene
    • C08J2323/06—Polyethene
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K2201/00—Specific properties of additives
    • C08K2201/013—Additives applied to the surface of polymers or polymer particles

Definitions

  • Ultra high molecular weight polyethylene is a unique form of polyethylene of extremely high molecular weight, where the molecular weight of commercial grade materials are typically in the range of 2 to 7 million.
  • the molecular weight of commodity polyethylene is typically in the range of 50,000 to 100,000, a factor of 25 or more times lower.
  • UHMWPE is the most widely used material for orthopedic implants that articulate, such as for hip, knee, ankle, elbow and shoulder joint replacement due to osteoarthritis.
  • a major concern for this material has been high wear rate with generation of microscopic wear particles over years of articulation.
  • a known outcome of a high polyethylene particulate burden is a condition known as osteolysis, which results in implant loosening with subsequent need for revision surgery.
  • UHMWPE is most often heat stabilized by raising the material temperature above the melting point of the material. This allows the trapped free radicals that did not participate in crosslinking to promote further crosslinking in the material, or to re-combine, rendering them to an inert state that will not promote premature oxidative degradation.
  • the melting process can cause the formation of a significant oxidized layer on the exterior of the material if the melting process is done in an oxygen-containing environment such as air, where sufficient oxygen is present to diffuse into the material in the molten state. This oxidized layer is removed during fabrication of the implant to prevent contamination of the implant with oxidatively-degraded UHMWPE.
  • WO2005074619A2 relates to methods for making highly crystalline cross-linked polymeric material, for example, highly crystalline cross-linked ultra-high molecular weight polyethylene (UHMWPE).
  • UHMWPE ultra-high molecular weight polyethylene
  • US2008215142A1 relates to methods for making cross-linked, oxidatively stable, and highly crystalline polymeric materials.
  • EP2578248A1 relates to an antioxidant combined with UHMWPE prior to subjecting the UHMWPE to crosslinking irradiation.
  • WO2012061499A1 relates to modified polymeric articles having modifying agents dispersed within and bonded to an interior region of the article and methods of modifying polymer materials used to form polymeric articles, and methods of making polymeric articles from polymer particles having modifying agents bonded thereto.
  • WO2004064618A2 relates to methods for making oxidation resistant medical devices that comprise polymeric materials, for example, ultra-high molecular weight polyethylene (UHMWPE).
  • UHMWPE ultra-high molecular weight polyethylene
  • EP2395048A2 is directed to polymer compositions including a protected antioxidant.
  • the compositions can also include a deprotected antioxidant, an unprotected antioxidant or both. Methods of producing compositions including a protected antioxidant and articles including a protected antioxidant are also described.
  • WO2009060043A2 relates to a process for producing an (ultra) high molecular weight polyethylene (HMWPE) article comprising: - incorporating into the HMWPE resin a Hindered Amine Light Stabilizer (HALS) and - cross-link the (U)HMWPE during or after molding the (U)HMWPE resin.
  • HALS Hindered Amine Light Stabilizer
  • the present disclosure provides a method of melt-stabilizing ultra high molecular weight polyethylene (UHMWPE).
  • UHMWPE ultra high molecular weight polyethylene
  • the method includes coating a solid material including UHMWPE with an antioxidant, to provide an antioxidant-coated solid material.
  • the method includes pre-irradiatively heating the antioxidant-coated solid material to diffuse the antioxidant therein, to provide an antioxidant-diffused solid material.
  • the method includes irradiating the antioxidant-diffused solid material, to provide an irradiated solid material.
  • the method includes post-irradiatively heating the irradiated solid material, the heating sufficient to melt at least part of the UHMWPE, to provide a heated material.
  • the method includes solidifying the heated material, to provide a melt-stabilized material.
  • the present invention provides a method of melt-stabilizing ultra high molecular weight polyethylene (UHMWPE).
  • the method includes coating a solid material including UHMWPE with a protected vitamin E antioxidant, to provide an antioxidant-coated solid material.
  • the protected vitamin E antioxidant is at least one of at least one of (a) and (b).
  • Protected vitamin E antioxidant (a) is a protected tocopherol or tocotrienol having the structure: or a salt thereof, or or a salt thereof.
  • R a is independently chosen from -H, -E, and substituted or unsubstituted (C 1 -C 10 )hydrocarbyl.
  • the variable E has the structure: or
  • the variables R 7 , R 8 , and R 9 are each independently chosen from -H, substituted or unsubstituted (C 1 -C 10 )alkyl, and substituted or unsubstituted (C 1 -C 10 )alkenyl.
  • Protected vitamin E antioxidant (b) is a hindered amine stabilizer-protected tocopherol or tocotrienol of formula (1): or a salt thereof.
  • the variables R 1 , R 2 , R 3 , and R 4 are each, independently, hydrogen or (Ci-C 10 )alkyl.
  • the variable R 5 is chosen from hydrogen, (C 1 -C 10 )alkyl, -O ⁇ , and -OR 11 wherein R 11 is hydrogen or (C 1 -C 10 )alkyl.
  • the variable Y represents the group:
  • variable R 6 is hydrogen, (C 1 -C 10 )alkyl, -E, or a radical of the formula:
  • the method includes pre-irradiatively heating the antioxidant-coated solid material to diffuse the antioxidant therein, to provide an antioxidant-diffused solid material.
  • the method includes irradiating the antioxidant-diffused solid material, to provide an irradiated solid material.
  • the method includes post-irradiatively heating the irradiated solid material, the heating sufficient to melt at least part of the UHMWPE, to provide a heated material.
  • the method also includes solidifying the heated material, to provide a melt-stabilized material.
  • a melt-stabilized ultra high molecular weight polyethylene (UHMWPE) material made by a method including coating a solid material including UHMWPE with an antioxidant, to provide an antioxidant-coated solid material is disclosed.
  • the method includes pre-irradiatively heating the antioxidant-coated solid material to diffuse the antioxidant therein, to provide an antioxidant-diffused solid material.
  • the method includes irradiating the antioxidant-diffused solid material, to provide an irradiated solid material.
  • the method includes post-irradiatively heating the irradiated solid material, the heating sufficient to melt at least part of the UHMWPE, to provide a heated material.
  • the method also includes solidifying the heated material, to provide the melt-stabilized material.
  • the method can include forming a UHMWPE material having less or no formation of an oxidized layer on the surface of the UHMWPE.
  • Medical-grade UHMWPE can represent a significant cost in the production of a medical implant including UHMWPE. Oxidation of the surface of UHMWPE during various steps, such as during melt-stabilization (e.g., melting after irradiation), results in the removal and discarding of the oxidized layer due to unsuitability for medical-implant preparation.
  • the method can form a UHMWPE material that is ready to form into a medical implant with less or no removal of a surface layer.
  • the method provides cost savings over other methods by decreasing the amount of UHMWPE that is wasted.
  • the method can avoid formation of a surface oxidation layer even with melt-stabilization in an oxygen-containing atmosphere (e.g., air).
  • the method provides costs savings by avoiding equipment, supplies, and time-consuming techniques needed for generating an oxygen-free or oxygen-depleted environment.
  • performing the method using a protected antioxidant provides a melt-stabilized crosslinked UHMWPE with a higher crosslinking density than other UHMWPEs with pre-irradiative addition of antioxidant, but having similar or greater post-irradiative resistance to oxidation and corresponding degradation.
  • the addition and diffusion of the antioxidant can be more convenient and can reduce processing costs as well as reducing costs related to oxidation.
  • diffusion of the antioxidant can be conducting during a consolidation process in situ, such as for semi-continuous processes such as ram extrusion or continuous processes such as extrusion.
  • the antioxidant can be applied to the material after consolidation of powder in an external layer.
  • diffusion of the antioxidant in an external layer of material can retard or lower infusion of lipids in vivo that may promote oxidation of UHMWPE.
  • the method can include targeting antioxidants that can retard crosslinking to regions of an implant that require higher mechanical property retention and that may not require the higher wear resistance provided by a higher crosslinking density.
  • Articulation can be lower or minimal in a region not requiring high wear resistance; for example, the rim of a hip implant liner can be subjected to low wear rates but is subjected to oxidative stresses and can require high mechanical property retention.
  • values expressed in a range format should be interpreted in a flexible manner to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited.
  • a range of "about 0.1% to about 5%” or "about 0.1% to 5%” should be interpreted to include not just about 0.1% to about 5%, but also the individual values (e.g., 1%, 2%, 3%, and 4%) and the sub-ranges (e.g., 0.1% to 0.5%, 1.1% to 2.2%, 3.3% to 4.4%) within the indicated range.
  • the acts can be carried out in any order without departing from the principles of the invention, except when a temporal or operational sequence is explicitly recited. Furthermore, specified acts can be carried out concurrently unless explicit claim language recites that they be carried out separately. For example, a claimed act of doing X and a claimed act of doing Y can be conducted simultaneously within a single operation, and the resulting process will fall within the literal scope of the claimed process.
  • substantially refers to a majority of or mostly, as in at least about 50%, 60%, 70%, 80%, 90%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9%, 99.99%, or at least about 99.999% or more, or 100%.
  • organic group refers to any carbon-containing functional group.
  • an oxygen-containing group such as an alkoxy group, aryloxy group, aralkyloxy group, oxo(carbonyl) group, a carboxyl group including a carboxylic acid, carboxylate, and a carboxylate ester
  • a sulfur-containing group such as an alkyl and aryl sulfide group
  • other heteroatom-containing groups such as an alkoxy group, aryloxy group, aralkyloxy group, oxo(carbonyl) group, a carboxyl group including a carboxylic acid, carboxylate, and a carboxylate ester
  • sulfur-containing group such as an alkyl and aryl sulfide group
  • other heteroatom-containing groups such as an alkyl and aryl sulfide group.
  • Non-limiting examples of organic groups include OR, OOR, OC(O)N(R) 2 , CN, CF 3 , OCF 3 , R, C(O), methylenedioxy, ethylenedioxy, N(R) 2 , SR, SOR, SO 2 R, SO 2 N(R) 2 , SO 3 R, C(O)R, C(O)C(O)R, C(O)CH 2 C(O)R, C(S)R, C(O)OR, OC(O)R, C(O)N(R) 2 , OC(O)N(R) 2 , C(S)N(R) 2 , (CH 2 ) 0-2 N(R)C(O)R, (CH 2 ) 0-2 N(R)N(R) 2 , N(R)N(R)C(O)R, N(R)N(R)C(O)OR, N(R)N(R)CON(R) 2 , N(R)SO 2 R
  • substituted as used herein in conjunction with a molecule or an organic group as defined herein refers to the state in which one or more hydrogen atoms contained therein are replaced by one or more non-hydrogen atoms.
  • functional group or “substituent” as used herein refers to a group that can be or is substituted onto a molecule or onto an organic group.
  • substituents or functional groups include, but are not limited to, a halogen (e.g., F, Cl, Br, and I); an oxygen atom in groups such as hydroxy groups, alkoxy groups, aryloxy groups, aralkyloxy groups, oxo(carbonyl) groups, carboxyl groups including carboxylic acids, carboxylates, and carboxylate esters; a sulfur atom in groups such as thiol groups, alkyl and aryl sulfide groups, sulfoxide groups, sulfone groups, sulfonyl groups, and sulfonamide groups; a nitrogen atom in groups such as amines, hydroxyamines, nitriles, nitro groups, N-oxides, hydrazides, azides, and enamines; and other heteroatoms in various other groups.
  • a halogen e.g., F, Cl, Br, and I
  • an oxygen atom in groups such as hydroxy groups, al
  • Non-limiting examples of substituents that can be bonded to a substituted carbon (or other) atom include F, Cl, Br, I, OR, OC(O)N(R) 2 , CN, NO, NO 2 , ONO 2 , azido, CF 3 , OCF 3 , R, O (oxo), S (thiono), C(O), S(O), methylenedioxy, ethylenedioxy, N(R) 2 , SR, SOR, SO 2 R, SO 2 N(R) 2 , SO 3 R, C(O)R, C(O)C(O)R, C(O)CH 2 C(O)R, C(S)R, C(O)OR, OC(O)R, C(O)N(R) 2 , OC(O)N(R) 2 , C(S)N(R) 2 , (CH 2 ) 0-2 N(R)C(O)R, (CH 2 )N(R)N(R) 2
  • alkyl refers to straight chain and branched alkyl groups and cycloalkyl groups having from 1 to 40 carbon atoms, 1 to about 20 carbon atoms, 1 to 12 carbons or, in some embodiments, from 1 to 8 carbon atoms.
  • straight chain alkyl groups include those with from 1 to 8 carbon atoms such as methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, and n-octyl groups.
  • branched alkyl groups include, but are not limited to, isopropyl, iso-butyl, sec-butyl, t-butyl, neopentyl, isopentyl, and 2,2-dimethylpropyl groups.
  • alkyl encompasses n-alkyl, isoalkyl, and anteisoalkyl groups as well as other branched chain forms of alkyl.
  • Representative substituted alkyl groups can be substituted one or more times with any of the groups listed herein, for example, amino, hydroxy, cyano, carboxy, nitro, thio, alkoxy, and halogen groups.
  • alkenyl refers to straight and branched chain and cyclic alkyl groups as defined herein, except that at least one double bond exists between two carbon atoms.
  • alkenyl groups have from 2 to 40 carbon atoms, or 2 to about 20 carbon atoms, or 2 to 12 carbon atoms or, in some embodiments, from 2 to 8 carbon atoms.
  • acyl refers to a group containing a carbonyl moiety wherein the group is bonded via the carbonyl carbon atom.
  • the carbonyl carbon atom is bonded to a hydrogen forming a "formyl” group or is bonded to another carbon atom, which can be part of an alkyl, aryl, aralkyl cycloalkyl, cycloalkylalkyl, heterocyclyl, heterocyclylalkyl, heteroaryl, heteroarylalkyl group or the like.
  • An acyl group can include 0 to about 12, 0 to about 20, or 0 to about 40 additional carbon atoms bonded to the carbonyl group.
  • An acyl group can include double or triple bonds within the meaning herein.
  • An acryloyl group is an example of an acyl group.
  • An acyl group can also include heteroatoms within the meaning herein.
  • a nicotinoyl group (pyridyl-3-carbonyl) is an example of an acyl group within the meaning herein.
  • Other examples include acetyl, benzoyl, phenylacetyl, pyridylacetyl, cinnamoyl, and acryloyl groups and the like.
  • the group containing the carbon atom that is bonded to the carbonyl carbon atom contains a halogen, the group is termed a "haloacyl" group.
  • An example is a trifluoroacetyl group.
  • aryl refers to cyclic aromatic hydrocarbon groups that do not contain heteroatoms in the ring.
  • aryl groups include, but are not limited to, phenyl, azulenyl, heptalenyl, biphenyl, indacenyl, fluorenyl, phenanthrenyl, triphenylenyl, pyrenyl, naphthacenyl, chrysenyl, biphenylenyl, anthracenyl, and naphthyl groups.
  • aryl groups contain about 6 to about 14 carbons in the ring portions of the groups.
  • Aryl groups can be unsubstituted or substituted, as defined herein.
  • Representative substituted aryl groups can be mono-substituted or substituted more than once, such as, but not limited to, a phenyl group substituted at any one or more of 2-, 3-, 4-, 5-, or 6-positions of the phenyl ring, or a naphthyl group substituted at any one or more of 2- to 8-positions thereof.
  • heterocyclyl refers to aromatic and non-aromatic ring compounds containing three or more ring members, of which one or more is a heteroatom such as, but not limited to, N, O, and S.
  • heteroaryl refers to aromatic ring compounds containing 5 or more ring members, of which, one or more is a heteroatom such as, but not limited to, N, O, and S; for instance, heteroaryl rings can have 5 to about 8-12 ring members.
  • a heteroaryl group is a variety of a heterocyclyl group that possesses an aromatic electronic structure.
  • heterocyclylalkyl refers to alkyl groups as defined herein in which a hydrogen or carbon bond of an alkyl group as defined herein is replaced with a bond to a heterocyclyl group as defined herein.
  • heterocyclyl alkyl groups include, but are not limited to, furan-2-yl methyl, furan-3-yl methyl, pyridine-3-yl methyl, tetrahydrofuran-2-yl ethyl, and indol-2-yl propyl.
  • alkoxy refers to an oxygen atom connected to an alkyl group, including a cycloalkyl group, as are defined herein.
  • linear alkoxy groups include but are not limited to methoxy, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy, and the like.
  • branched alkoxy include but are not limited to isopropoxy, sec-butoxy, tert-butoxy, isopentyloxy, isohexyloxy, and the like.
  • cyclic alkoxy include but are not limited to cyclopropyloxy, cyclobutyloxy, cyclopentyloxy, cyclohexyloxy, and the like.
  • An alkoxy group can include about 1 to about 12, about 1 to about 20, or about 1 to about 40 carbon atoms bonded to the oxygen atom, and can further include double or triple bonds, and can also include heteroatoms.
  • an allyloxy group or a methoxyethoxy group is also an alkoxy group within the meaning herein, as is a methylenedioxy group in a context where two adjacent atoms of a structure are substituted therewith.
  • amine refers to primary, secondary, and tertiary amines having, e.g., the formula N(group) 3 wherein each group can independently be H or non-H, such as alkyl, aryl, and the like.
  • Amines include but are not limited to R-NH 2 , for example, alkylamines, arylamines, alkylarylamines; R 2 NH wherein each R is independently selected, such as dialkylamines, diarylamines, aralkylamines, heterocyclylamines and the like; and R 3 N wherein each R is independently selected, such as trialkylamines, dialkylarylamines, alkyldiarylamines, triarylamines, and the like.
  • amine also includes ammonium ions as used herein.
  • halo means, unless otherwise stated, a fluorine, chlorine, bromine, or iodine atom.
  • hydrocarbon or “hydrocarbyl” as used herein refers to a molecule or functional group, respectively, that includes carbon and hydrogen atoms.
  • the term can also refer to molecule or functional group that normally includes both carbon and hydrogen atoms but wherein all the hydrogen atoms are substituted with other functional groups.
  • hydrocarbyl refers to a functional group derived from a straight chain, branched, or cyclic hydrocarbon, and can be alkyl, alkenyl, alkynyl, aryl, cycloalkyl, acyl, or any combination thereof. Hydrocarbyl groups can be shown as (C a -C b )hydrocarbyl, wherein a and b are integers and mean having any of a to b number of carbon atoms.
  • (C 1 -C 4 )hydrocarbyl means the hydrocarbyl group can be methyl (C 1 ), ethyl (C 2 ), propyl (C 3 ), or butyl (C 4 ), and (C 0 -C b )hydrocarbyl means in certain embodiments there is no hydrocarbyl group.
  • M n number-average molecular weight
  • solvent refers to a liquid that can dissolve a solid, liquid, or gas.
  • solvents are silicones, organic compounds, water, alcohols, ionic liquids, and supercritical fluids.
  • air refers to a mixture of gases with a composition approximately identical to the native composition of gases taken from the atmosphere, generally at ground level. In some examples, air is taken from the ambient surroundings. Air has a composition that includes approximately 78% nitrogen, 21% oxygen, 1% argon, and 0.04% carbon dioxide, as well as small amounts of other gases.
  • room temperature refers to a temperature of about 15 °C to 28 °C.
  • standard temperature and pressure refers to 20 °C and 101 kPa.
  • coating refers to a continuous or discontinuous layer of material on the coated surface, wherein the layer of material can penetrate the surface and can fill areas such as pores, wherein the layer of material can have any three-dimensional shape, including a flat or curved plane.
  • a coating can be formed on one or more surfaces, any of which may be porous or nonporous, by immersion in a bath of coating material.
  • surface refers to a boundary or side of an object, wherein the boundary or side can have any perimeter shape and can have any three-dimensional shape, including flat, curved, or angular, wherein the boundary or side can be continuous or discontinuous. While the term surface generally refers to the outermost boundary of an object with no implied depth, when the term 'pores' is used in reference to a surface, it refers to both the surface opening and the depth to which the pores extend beneath the surface into the substrate.
  • polymer refers to a molecule having at least one repeating unit and can include copolymers.
  • salts having a positively charged counterion can include any suitable positively charged counterion.
  • the counterion can be ammonium(NH4 + ), or an alkali metal such as sodium (Na + ), potassium (K + ), or lithium (Li + ).
  • the counterion can have a positive charge greater than +1, which can in some embodiments complex to multiple ionized groups, such as Zn 2+ , Al 3+ , or alkaline earth metals such as Ca 2+ or Mg 2+ .
  • salts having a negatively charged counterion can include any suitable negatively charged counterion.
  • the counterion can be a halide, such as fluoride, chloride, iodide, or bromide.
  • the counterion can be nitrate, hydrogen sulfate, dihydrogen phosphate, bicarbonate, nitrite, perchlorate, iodate, chlorate, bromate, chlorite, hypochlorite, hypobromite, cyanide, amide, cyanate, hydroxide, permanganate.
  • the counterion can be a conjugate base of any carboxylic acid, such as acetate or formate.
  • a counterion can have a negative charge greater than -1, which can in some embodiments complex to multiple ionized groups, such as oxide, sulfide, nitride, arsenate, phosphate, arsenite, hydrogen phosphate, sulfate, thiosulfate, sulfite, carbonate, chromate, dichromate, peroxide, or oxalate.
  • ionized groups such as oxide, sulfide, nitride, arsenate, phosphate, arsenite, hydrogen phosphate, sulfate, thiosulfate, sulfite, carbonate, chromate, dichromate, peroxide, or oxalate.
  • the polymers described herein can terminate in any suitable way.
  • the polymers can terminate with an end group that is independently chosen from a suitable polymerization initiator, -H, -OH, a substituted or unsubstituted (C 1 -C 20 )hydrocarbyl (e.g., (C 1 -C 10 )alkyl or (C 6 -C 20 )aryl) interrupted with 0, 1, 2, or 3 groups independently selected from -O-, substituted or unsubstituted -NH-, and -S-, a poly(substituted or unsubstituted (Ci-C 20 )hydrocarbyloxy), and a poly(substituted or unsubstituted (C 1 -C 20 )hydrocarbylamino).
  • a suitable polymerization initiator e.g., a substituted or unsubstituted (C 1 -C 20 )hydrocarbyl (e.g., (C 1
  • Ultra high molecular weight polyethylene UHMWPE
  • Oxidation of polyethylene can occur through a free radical pathway, as shown in the following sequence: RH + IN ⁇ R ⁇ Initiation R ⁇ + O 2 ⁇ ROO ⁇ ROO- + RH ⁇ ROOH + R ⁇ Propagation ROOH > RO ⁇ + HO ⁇ RO ⁇ + RH ⁇ ROH + R ⁇ Chain Branching HO ⁇ + RH ⁇ HOH + R ⁇ ROO ⁇ (RO ⁇ etc.) ⁇ Inert Products Termination ROO ⁇ + AH ⁇ ROOH + A ⁇ RO- + AH ⁇ ROH + A- Inhibition (stabilization) HO ⁇ + AH > HOH + A ⁇ wherein
  • the present invention provides a method of melt-stabilizing ultra high molecular weight polyethylene (UHMWPE).
  • the method can include coating a solid material including UHMWPE with an antioxidant, to provide an antioxidant-coated solid material.
  • the method can include pre-irradiatively heating the antioxidant-coated solid material to diffuse the antioxidant therein, to provide an antioxidant-diffused solid material.
  • the method can include irradiating the antioxidant-diffused solid material, to provide an irradiated solid material.
  • the method can include post-irradiatively heating the irradiated solid material, the heating sufficient to melt at least part of the UHMWPE, to provide a heated material.
  • the method can include solidifying the heated material, to provide a melt-stabilized material.
  • one or more agents can be added to the material including UHMWPE. Such addition can be accomplished during any stage of preparation but may be desirable after any heat treatments are performed to reduce the likelihood of deactivation of the bioactive agent.
  • agents include, but are not limited to, an antibiotic, a steroid, a drug, a growth factor such as bone morphogenic protein, an osteocyte, an osteoclast or other cells, a vitamin, a chondroitin, a glucosamine, a glycosoaminglycan, high energy phosphates such as phosphoenolpyruvate, ATP, 5'-AMP, and other small molecule biologics or other chemical or biological agents.
  • the material including UHMWPE can be loaded with stem cells, and the material can act as a scaffold to permit growth and differentiation of bone or cartilage within the polymer framework.
  • the presence of an antioxidant in the material including UHMWPE can act to prevent degradation of the scaffold in its use environment and may also provide some oxidative protection to the bioactive agent or stem cells loaded into the scaffold.
  • the method of melt-stabilizing UHMWPE can include any suitable physical manipulation before, between, or after any suitable steps of the method (e.g., coating, pre-irradiatively heating, preheating, irradiating, post-irradiatively heating, or solidifying), such as molding, compressing, consolidating, removing material from, or otherwise processing to provide a desired shape, part size, or other physical attributes to render the part suitable for its intended use.
  • any suitable physical manipulation before, between, or after any suitable steps of the method e.g., coating, pre-irradiatively heating, preheating, irradiating, post-irradiatively heating, or solidifying
  • molding compressing, consolidating, removing material from, or otherwise processing to provide a desired shape, part size, or other physical attributes to render the part suitable for its intended use.
  • additional components may be combined with the material including UHMWPE before, between, or after any suitable steps of the method (e.g., any of coating, pre-irradiatively heating, preheating, irradiating, post-irradiatively heating, or solidifying).
  • tribological components such as metal and/or ceramic articulating components and/or preassembled bipolar components may be joined with the material including UHMWPE.
  • metal backing e.g., plates or shields
  • surface components such as a trabecular metal, fiber metal, Sulmesh TM coating, meshes, cancellous titanium, and/or metal or polymer coatings may be added to or joined with the material including UHMWPE.
  • Radiomarkers or radiopacifiers such as tantalum, steel and/or titanium balls, wires, bolts or pegs may be added.
  • Locking features such as rings, bolts, pegs, snaps and/or cements/adhesives can be added.
  • the material including the UHMWPE is a solid monolithic material, such as a single solid mass, a non-particulate form, a non-powder, a bar, or a form. Any suitable proportion of the solid material including UHMWPE can be the UHMWPE, such as about 1 wt% to about 100 wt% of the solid material, about 90 wt% to about 100 wt%, or about 1 wt% or less, or about 2, 3, 4, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 96, 97, 98, 99, or about 99.9 wt% or more.
  • the UHMWPE can form a homogeneous or heterogeneous mixture with other components in the solid material.
  • UHWMPE is a semi crystalline, linear homopolymer of ethylene, which in some embodiments can be produced by stereospecific polymerization with a Ziegler-Natta catalyst at low pressure (6-8 bar) and low temperature (66-80°C).
  • the synthesis of UHMWPE can result in a fine granular powder.
  • the molecular weight and its distribution can be controlled by process parameters such as temperature, time and pressure.
  • UHMWPE generally has a molecular weight of at least about 2,000,000 g/mol.
  • Suitable UHMWPE materials for use as raw materials may be in the form of a powder or mixture of powders. Examples of suitable UHMWPE materials include GUR ® 1020 and GUR ® 1050 available from Ticona Engineering Polymers.
  • UHMWPE powder can be processed and consolidated to form a solid monolithic material.
  • the solid material including UHMWPE can include any other suitable component.
  • the UHWMPE can be combined with another crosslinkable polymer.
  • the crosslinkable polymer can be any polymer that is crosslinkable using radiation, a chemical crosslinking agent or that can be physically cross-linked under suitable conditions.
  • the polymer can be a thermoplastic polymer such as, for example, an acrylonitrile butadiene styrene (ABS) polymer, an acrylic polymer, a celluloid polymer, a cellulose acetate polymer, a cycloolefin copolymer (COC), an ethylenevinyl acetate (EVA) polymer, an ethylene vinyl alcohol (EVOH) polymer, a fluoroplastic, an ionomer, an acrylic/PVC alloy, a liquid crystal polymer (LCP), a polyacetal polymer (POM or acetal), a polyacrylate polymer, a polyacrylonitrile polymer (PAN or acrylonitrile), a polyamide polymer (PA or nylon), a polyamide-imide polymer (PAI), a polyaryletherketone polymer (PAEK or ketone), a polybutadiene polymer (PBD), a polybutylene polymer (PB), a poly(ABS
  • UHMWPE ultra low molecular weight polyethylene
  • HMWPE high molecular weight polyethylene
  • HDPE high density polyethylene
  • HDXLPE high density cross-linked polyethylene
  • PEX or XLPE medium density polyethylene
  • MDPE low density polyethylene
  • LDPE low density polyethylene
  • LLDPE linear low density polyethylene
  • VLDPE very low density polyethylene
  • a polypropylene can be used.
  • a polypropylene may be particularly desirable where the final product is a mesh, stent, breast implant material, suture material or other medical device.
  • a polypropylene may be used as one layer in a multi-layered medical device.
  • Illustrative polypropylenes include, but are not limited to, a homopolymeric polypropylene, a block copolymeric polypropylene, and a random copolymeric polypropylene.
  • the polymers used in the compositions described herein can be copolymerized with one or more monomers or polymers.
  • the solid material including UHMWPE is a consolidated mixture of UHMWPE and any other suitable component.
  • the solid material including UHMWPE can include one or more suitable additives that impart a desired physical or chemical property.
  • suitable additives include, but are not limited to, radiopaque materials, antimicrobial materials such as silver ions, antibiotics, and microparticles and/or nanoparticles serving various functions. Preservatives, colorants and other conventional additives may also be used.
  • the solid material including UHMWPE can be prepared by a method including blending a UHMWPE powder with other suitable materials, such as a blend with another polymer or a blend with an antioxidant.
  • suitable materials such as a blend with another polymer or a blend with an antioxidant.
  • Such processes include physical mixing, mixing with the aid of a solvent, mixing with the aid of a solvent (e.g., CO 2 ) under supercritical temperature and pressure conditions, and ultrasonic mixing.
  • the solid material including UHMWPE can include an antioxidant, such as any one or more suitable antioxidants described herein.
  • the one or more antioxidants can be present in any suitable concentration, such as any concentration described herein.
  • the one or more antioxidant can be present in any type of distribution in the solid material including UHMWPE, such as a substantially homogeneous distribution.
  • the solid material including UHMWPE can be substantially free of antioxidants.
  • the method includes coating the solid material including UHMWPE with an antioxidant, to provide an antioxidant-coated solid material.
  • the antioxidant can be applied neat or as part of a liquid composition including the antioxidant.
  • the coating can be any suitable coating method that applies the antioxidant sufficiently such that the antioxidant can penetrate a surface layer of the solid material including UHMWPE.
  • the coating can be performed using any suitable coating process, such as one or more of brushing, dipping, soaking, immersion with agitation or stirring, spraying, and the like.
  • the coating is performed such that the antioxidant does not penetrate past a depth of 0 mm of the surface of application, to provide an antioxidant-coated solid material.
  • the coating can be sufficient for the antioxidant to infuse (e.g., penetrate) into a surface layer of the solid material including UHMWPE that includes any suitable depth from the surface of the solid material including UHMWPE where the coating is applied, such as about 0 mm (e.g., only present on or very near the surface of application), about 0 mm to about 1 mm, about 0 mm to about 10 mm deep, about 1 mm to about 10 mm deep, about 0 mm to about 20 mm deep, about 1 mm or less, or about 1.5 mm, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or about 20 mm or more.
  • about 0 mm e.g., only present on or very near the surface of application
  • the coating can be performed such that the antioxidant does not penetrate past a certain depth of the solid material including UHMWPE.
  • the coating penetrates the solid material including UHMWPE no deeper than about 1 mm or less, or about 1.5 mm, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 mm, or about 20 mm or more.
  • the coating does not penetrate past the surface layer, wherein the non-surface layer portions of the solid material including UHMWPE are substantially free of the antioxidant.
  • the coating penetrates the solid material including UHMWPE such that in at least one of the antioxidant-coated solid material the antioxidant is present to a depth of about 0 mm to about 1 mm, about 0 mm to about 10 mm deep, about 1 mm to about 10 mm deep, about 0 mm to about 20 mm deep, about 1 mm or less, or about 1.5 mm, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or about 20 mm or more.
  • the antioxidant can diffuse through the UHMWPE material, such as during pre-irradiative heating.
  • the antioxidant added via the coating can protect the UHMWPE in the solid material including UHMWPE from oxidation by oxygen in the air during a subsequent melt-stabilization.
  • the coating can allow the antioxidant to penetrate and subsequently diffuse into the UHMWPE on the surface of the solid material including UHMWPE and protect the UHMWPE therein from oxidation by oxygen in the air, as described herein.
  • the coating can include coating any suitable proportion of the total surface area of the solid material including UHMWPE.
  • the coating can include selective coating or uniform coating of the solid material including UHMWPE.
  • the coating can be sufficient to contact the antioxidant with at least some of the UHMWPE in the solid material including UHMWPE, wherein the UHMWPE can be on the surface or proximate to the surface (e.g., within 1 mm to about 10 mm).
  • the method can optionally include only coating the part of the surface of the solid material that includes the UHMWPE or that is proximate to UHMWPE.
  • the coating can include coating about 1% to about 100% of the total surface area of the solid material, about 50% to about 100%, about 90% to about 100%, or about 1% or less, or about 2%, 3, 4, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 99.5, 99.9, 99.99, or about 99.999% or more.
  • the coating can be sufficient to provide any suitable weight gain to the solid material including UHM WPE, such that the antioxidant is suitably applied to the solid material including UHMWPE.
  • the coating can be sufficient to provide a weight gain of about 0.000,01 g per cm 2 surface area of the solid material to about 50 g/cm 2 surface area, about 0.000,1 g/cm 2 surface area to about 1 g/cm 2 surface area, about 0.000,01 g/cm 2 surface area or less, or about 0.000,1 g/cm 2 surface area, 0.000,2, 0.000,5, 0.000,8, 0.001, 0.005, 0.01, 0.05, 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 6, 7, 8, 9, 10, 12, 14, 16, 18, 20, 25, 30, 35, 40, 45, or about 50 g/cm 2 surface area or more.
  • Liquid composition including the antioxidant.
  • the coating of the solid material including UHMWPE with an antioxidant can include coating the solid material with neat antioxidant or coating the solid material with a liquid composition including the antioxidant.
  • the liquid composition can be a solution of the one or more antioxidants in one or more suitable solvents (e.g., carrier liquids).
  • the neat antioxidant can be applied if it is a liquid with low enough viscosity, or it can be dissolved in a suitable carrier fluid, such as if it is a viscous liquid or solid.
  • the concentration of the antioxidant can be varied to control the amount of antioxidant infused and diffused in the solid material including UHMWPE.
  • the antioxidant or the multiple antioxidants can be any suitable wt% of the liquid composition, such as about 0.01 wt% to about 100 wt% of the liquid composition, about 1 wt% to about 100 wt%, about 5 wt% to about 100 wt%, about 0.01 wt% or less, or about 0.1 wt%, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 99.5, 99.9, 99.99, or about 99.999 wt% of the liquid composition or more.
  • the carrier liquid can be any suitable carrier liquid.
  • the carrier liquid can be water (e.g., di-ionized water), or an aqueous solution (e.g., saline).
  • the carrier liquid can be an organic solvent, such as any suitable organic solvent, such as acetone, methanol, ethanol, or propanol (e.g., isopropanol or normal propanol).
  • the carrier liquid can be any suitable proportion of the liquid composition including the antioxidant, such as about 1 wt% to about 99 wt%, 5 wt% to about 95 wt%, or about 1 wt% or less, or about 2 wt%, 3, 4, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98, or about 99 wt% or more.
  • the antioxidant such as about 1 wt% to about 99 wt%, 5 wt% to about 95 wt%, or about 1 wt% or less, or about 2 wt%, 3, 4, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98, or about 99 wt% or more.
  • the method can include heating the material including UHMWPE in subsequent steps sufficiently such that one or more of the one or more solvents is substantially completely evaporated from the material including UHMWPE, for example, such that only the one or more antioxidants are left behind.
  • the liquid composition can include any suitable material in addition to the one or more antioxidants and the one or more optional carrier fluids.
  • the liquid composition includes one or more organic peroxides.
  • the one or more organic peroxides can provide crosslinking, reducing or eliminating a subsequent irradiation crosslinking step.
  • the antioxidant can be any suitable antioxidant.
  • the antioxidant can be a free-radical scavenger, such that the antioxidant can neutralize a free-radical before the free-radical can react with oxygen to form an oxidized species.
  • the antioxidant can be any suitable antioxidant that allows the method to effectively produce materials including UHMWPE that can resist oxidation, such as melt-stabilized materials including UHMWPE having less or no oxidized layer when melt-stabilized in an oxygen-containing environment.
  • One antioxidant can be used, or multiple antioxidants can be used.
  • the one or more antioxidants can form any suitable wt% of the material including the UHMWPE, such as the antioxidant-coated solid material, the antioxidant-diffused solid material, the irradiated solid material, the heated material, or the melt-stabilized material, such as about 0.01 wt% to about 20 wt%, about 0.1 wt% to about 5 wt%, about 0.01 wt% or less, or about 0.05 wt%, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.2, 1.4, 1.6, 1.8, 2, 2.2, 2.4, 2.6, 2.8, 3, 3.5, 4, 4.5, 5, 6, 7, 8, 9, 10, 15, or about 20 wt% or more.
  • the antioxidant can have a molecular weight that allows the antioxidant to diffuse effectively during the pre-irradiative heating.
  • the antioxidant can have a molecular weight of less than 10,000 g/mol, or less than 5,000, about 100 to about 5,000, about 100 to about 2,000, about 100 or less, or about 200, 300, 400, 500, 600, 700, 800, 900, 1,000, 1,200, 1,400, 1,600, 1,800, 2,000, 2,500, 3,000, 3,500, 4,000, 4,500, 5,000, 6,000, 7,000, 8,000, 9,000, or about 10,000 g/mol or more.
  • the antioxidant can be at least one of a tocopherol, a tocopherol phosphite, a tocotrienol, vitamin E, vitamin E acetate, a protected vitamin E, a rosemary oil, pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), butanedioic acid dimethyl ester/4-hydroxy-2,2,6,6-tetramethyl-1-piperidine ethanol copolymer, tannic acid, bilberry extract, vitamin C, a carotene, a flavonoid, an isoflavonoid, a neoflavonoid, a lignin, quinine, ubiquinone, vitamin K1, a metal, glutathione, propyl gallate, octyl gallate, lauryl gallate, resveratrol, rosmarinic acid, rutin, 5-aminosalicy
  • the antioxidant can be at least one of vitamin E, vitamin E acetate, pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), butanedioic acid dimethyl ester/4-hydroxy-2,2,6,6-tetramethyl-1-piperidine ethanol copolymer, tannic acid, and bilberry extract.
  • the antioxidant can be at least one of racemic alpha-tocopherol, RRR-alpha-tocopherol, SRR-alpha-tocopherol, SSR-alpha-tocopherol, SRS-alpha-tocopherol, SSS-alpha-tocopherol, RSR-alpha-tocopherol, RRS-alpha-tocopherol, RSS-alpha-tocopherol, racemic beta-tocopherol, RRR-beta-tocopherol, SRR-beta-tocopherol, SSR-beta-tocopherol, SRS-beta-tocopherol, SSS-beta-tocopherol, RSR-beta-tocopherol, RRS-beta-tocopherol, RSS-beta-tocopherol, racemic gamma-tocopherol, RRR-gamma-tocopherol, SRR-gamma-tocopherol, SSR-gamma-tocop
  • a tocopherol can have the structure:
  • R 1A , R 2A , and R 3A are each independently selected from hydrogen, substituted or unsubstituted (C 1 -C 10 )alkyl, and substituted or unsubstituted (C 1 -C 10 )alkenyl.
  • the stereochemistry of the tocopherol can be racemic or at least one of RRR, SRR, SSR, SRS, RSR, RRS, RSS, and SSS.
  • R 1A , R 2A , and R 3A are each (C 1 -C 10 )alkyl, such as methyl (e.g., alpha-tocopherol).
  • R 1A and R 3A are each (C 1 -C 10 )alkyl, such as methyl, and R 2A is hydrogen (beta-tocopherol). In some embodiments, R 2A and R 3A are each (C 1 -C 10 )alkyl, such as methyl, and R 1A is hydrogen (gamma-tocopherol). In some embodiments, R 1A and R 2A are each hydrogen and R 3A is (C 1 -C 10 )alkyl, such as methyl (delta-tocopherol).
  • a tocotrienol can have the structure:
  • R 1B , R 2B , and R 3B are each independently selected from hydrogen, substituted or unsubstituted (C 1 -C 10 )alkyl, and substituted or unsubstituted (C 1 -C 10 )alkenyl.
  • the stereochemistry of the tocotrienol can be racemic or at least one of R and S.
  • R 1B , R 2B , and R 3B are each (C 1 -C 10 )alkyl, such as methyl (e.g., alpha-tocotrienol).
  • R 1B and R 3B are each (C 1 -C 10 )alkyl, such as methyl, and R 2B is hydrogen (beta-tocotrienol). In some embodiments, R 2B and R 3B are each (C 1 -C 10 )alkyl, such as methyl, and R 1B is hydrogen (gamma-tocotrienol). In some embodiments, R 1B and R 2B are each hydrogen and R 3B is (C 1 -C 10 )alkyl, such as methyl (delta-tocotrienol). A tocopherol or tocotrienol can be naturally occurring or synthetic.
  • the antioxidant can be at least one of a hindered amine stabilizer or a hindered phenol stabilizer.
  • the antioxidant can be at least one of 4-Allyloxy-2-hydroxybenzophenone, 1-aza-3,7-dioxabicyclo[3.3.0]octane-5-methanol, 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol, 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol, 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methylphenol, 2-[3-(2H-benzotriazol-2-yl)-4-hydroxyphenyl]ethyl methacrylate, 2-(2H-benzotriazol-2-yl)-4-methyl-6-(2-propenyl)phenol, 2-(2H-benzotriazol-2-yl)
  • the hindered amine stabilizer is at least one of a 2,2,6,6-tetra((C 1 -C 50 )hydrocarbyl)-4-piperidyl diester of HOC(O)-(C 1 -C 50 )hydrocarbyl-C(O)OH, a 2,2,6,6-tetramethyl-4-piperidyl diester of HOC(O)-(C 1 -C 50 )hydrocarbyl-C(O)OH, bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, 1,2,2,6,6-penta((C 1 -C 50 )hydrocarbyl)-4-piperidyl diester of HOC(O)-(C 1 -C 50 )hydrocarbyl-C(O)OH, a 1,2,2,6,6-pentamethyl-4-piperidyl diester of HOC(O)-(C 1 -C 50 )hydrocarbyl-C(O)OH,
  • the antioxidant can be a protected antioxidant.
  • a protected antioxidant can be advantageous because it can avoid or reduce acting as an antioxidant during irradiative crosslinking, but after irradiative crosslinking (and deprotection) can act as an antioxidant to reduce oxidation and corresponding degradation of the UHMWPE. By avoiding or reducing antioxidant activity during crosslinking, a higher crosslinking density can be achieved.
  • the antioxidant is a protected tocopherol or tocotrienol having the structure: or a salt thereof, or or a salt thereof.
  • R a can be independently chosen from -H, -E, and substituted or unsubstituted (C 1 -C 10 )hydrocarbyl.
  • the variable E can have the structure: or
  • the variables R 7 , R 8 , and R 9 are each independently chosen from -H, substituted or unsubstituted (C 1 -C 10 )alkyl, and substituted or unsubstituted (C 1 -C 10 )alkenyl.
  • the method can include converting at least some of protected tocopherol or tocotrienol to a compound of the formula E: OH, such as after the irradiative crosslinking.
  • the antioxidant can be a hindered amine stabilizer-protected tocopherol or tocotrienol of formula (I): or a salt thereof.
  • the variables R 1 , R 2 , R 3 , and R 4 can be each, independently, hydrogen or (C 1 -C 10 )alkyl.
  • the variable R 5 can be chosen from hydrogen, (C 1 -C 10 )alkyl, -O ⁇ , and -OR 11 wherein R 11 can be hydrogen or (C 1 -C 10 )alkyl.
  • the variable E can have the structure: or
  • the variables R 7 , R 8 , and R 9 can be each independently chosen from -H, substituted or unsubstituted (C 1 -C 10 )alkyl, and substituted or unsubstituted (C 1 -C 10 )alkenyl.
  • the variable Y can represent the group:
  • variable R 6 can be hydrogen, (C 1 -C 10 )alkyl, -E, or a radical of the formula:
  • the one or more compounds of the formula (1) can be substantially uniformly distributed throughout the ultrahigh molecular weight polyethylene.
  • the method include converting at least some of the compound of the formula (I) to a compound of the formula E-OH, after the irradiating step.
  • the group E-O- can be a vitamin E radical.
  • the group R 6 -O- can be a vitamin E radical.
  • the variable R 6 can be a radical of the formula:
  • the variables R 1 , R 2 , R 3 , R 4 , and R 5 can be each, independently, (C 1 -C 10 )alkyl.
  • the variables R 1 , R 2 , R 3 , R 4 , and R 5 can be each methyl.
  • the variable Y can represent the group:
  • the method can include pre-irradiatively heating the antioxidant-coated solid material.
  • the pre-irradiative heating diffuses the antioxidant in the solid material.
  • the pre-irradiative heating provides an antioxidant-diffused solid material.
  • the pre-irradiative heating can be sufficient to at least partially diffuse the one or more antioxidants in the antioxidant-coated solid material.
  • the pre-irradiative heating can drive the antioxidant into the interior of the material.
  • the distance of the diffusion can be dependent on characteristics of the specific antioxidant such as molecular weight and similarity of solubility parameter with respect to UHMWPE. Migration distance and rate can also depend on the physical state of the antioxidant; for example, the diffusion distance can be greater when the melting point of the antioxidant is below the temperature achieved during the pre-irradiative heating.
  • the pre-irradiative heating can melt any suitable amount of the antioxidant-diffused solid material, or of the UHMWPE in the antioxidant-diffused solid material, such as about 0 vol% to about 100 vol%, or about 1 vol% or less, or about 2 vol%, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 96, 97, 98, or about 99 vol% or more.
  • the heating is sufficient to at least partially diffuse the one or more antioxidants in the antioxidant-coated solid material.
  • the method can include pre-irradiatively heating the antioxidant-diffused solid material in an environment including oxygen, the heating sufficient to melt at least part of the UHMWPE, to provide a heated material.
  • the method includes heating the antioxidant-diffused solid material in an environment substantially free of oxygen.
  • Various embodiments of the present invention provide a means to reduce the oxidized layer that forms during pre-irradiative heating of a material including UHMWPE in an oxygen-containing environment such as air.
  • the antioxidant can scavenge the free radicals present in the outer layer that would normally be oxidized.
  • the pre-irradiative heating can occur in an environment including any suitable amount of oxygen.
  • the heating can occur in an environment including ambient air, having about 20-21 vol% oxygen.
  • the heating can occur in an environment having about 1 vol% to about 50 vol% oxygen, about 10 vol% to about 30 vol% oxygen, about 1 vol% oxygen or less, or about 2 vol%, 3, 4, 5, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, or about 50 vol% oxygen or more.
  • the pre-irradiative heating heats the antioxidant-diffused solid material to any suitable temperature, such as about 50 °C to about 300 °C, about 80 °C to about 250 °C, about 130 °C to about 160 °C, about 50 °C or less, or about 60 °C, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 220, 240, 260, 280, or about 300 °C or more.
  • the temperature achieved can be a temperature below the melting point (e.g., about 138 °C), or above the melting point.
  • the antioxidant-diffused solid material can be heated for any suitable duration, such as about 1 minute to about 7 days, or about 1 hour to about 48 hours, or about 1 minute or less, or about 2 minutes, 3, 4, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55 minutes, 1 hour, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23 hours, 1 day, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5 days, or about 7 days or more.
  • the pre-irradiative heating can be sufficient to form a substantially homogenous distribution of the antioxidant in a surface layer of the antioxidant-diffused solid material.
  • the surface layer can be a layer of any suitable depth as measured from the outside of the material, such as about 0 mm to about 1 mm deep, about 0 mm to about 10 mm deep, about 1 mm to about 10 mm deep, about 0 mm to about 20 mm deep, about 1 mm or less, or about 1.5 mm, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or about 20 mm deep or more.
  • the pre-irradiative heating can be sufficient to allow the antioxidant (e.g., at least some of the antioxidant) to penetrate to a depth of at least about 1 mm from a surface (e.g., a surface where antioxidant was coated) of the antioxidant-diffused solid material, or about 2 mm, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or about 20 mm from a surface.
  • the antioxidant e.g., at least some of the antioxidant
  • the pre-irradiative heating can be sufficient to allow the antioxidant (e.g., at least some of the antioxidant) to penetrate to a depth of at least about 1 mm from a surface (e.g., a surface where antioxidant was coated) of the antioxidant-diffused solid material, or about 2 mm, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or about 20 mm from a surface.
  • the pre-irradiative heating can optionally include cooling prior to the irradiation (e.g., prior to an optional preheating step, or directly prior to the irradiation).
  • the cooling can be to any temperature below the melting point of the heated material, such as to room temperature.
  • the cooling can occur in ambient conditions, or the cooling can occur in a chilled environment.
  • the cooling can occur in any medium, such as in a gas (e.g., air) or in a liquid (e.g., water).
  • the method can include preheating prior to irradiation (e.g., warm-irradiating). In other embodiments, the method can be free of preheating prior to irradiation.
  • the preheating can be the same as the pre-irradiative heating, or the preheating and the pre-irradiative heating can be different heating steps.
  • the pre-irradiative heating can be preheating to or above a preheat temperature, to provide a preheated antioxidant-diffused solid material, wherein the irradiating includes irradiating the preheated antioxidant diffused solid material.
  • the pre-irradiative heating and preheating can be separate steps, wherein after the pre-irradiative heating the antioxidant-diffused solid material that was pre-irradiatively heated is preheated to at or above a preheat temperature to provide a preheated antioxidant-diffused solid material, wherein the irradiating includes irradiating the preheated antioxidant-diffused solid material.
  • the preheating can include heating to a temperature above room temperature and below or above the melting point of the UHMWPE or mixture of UHMWPE and other components, such as about 50 °C to about 300 °C, about 80 °C to about 250 °C, about 130 °C to about 160 °C, about 50 °C or less, or about 55 °C, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 140, 145, 150, 160, 170, 180, 190, 200, 220, 240, 260, 280, or about 300 °C or more, such that at the time of irradiation onset the material has a preheated temperature.
  • the preheating can be performed for any suitable amount of time, such as about 1 minute to about 7 days, or about 1 hour to about 48 hours, or about 1 minute or less, or about 2 minutes, 3, 4, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55 minutes, 1 hour, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23 hours, 1 day, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5 days, or about 7 days or more.
  • any suitable amount of time such as about 1 minute to about 7 days, or about 1 hour to about 48 hours, or about 1 minute or less, or about 2 minutes, 3, 4, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55 minutes, 1 hour, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23 hours, 1 day, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5 days, or about
  • the method includes irradiating the antioxidant-diffused material with an electron beam, to provide an irradiated solid material.
  • the antioxidant-diffused material can be preheated, or no preheating occurs prior to irradiation (e.g., the antioxidant-diffused material can be approximately ambient temperature or room temperature when irradiation begins).
  • the irradiating can crosslink the UHMWPE in the antioxidant-diffused solid material.
  • irradiation can be visible light radiation, infrared radiation, ultraviolet radiation, electron beam radiation, gamma radiation, or X-ray radiation.
  • the radiation can be obtained from any suitable source such as an atomic pile, a resonant transformer accelerator, a Van de Graaff electron accelerator, a Linac electron accelerator, a betatron, a synchrotron, a cyclotron, or the like. Radiation from these sources will produce ionizing radiation such as electrons, protons, neutrons, deuterons, gamma rays, X-rays, alpha particles, or beta particles.
  • a sufficient radiation dose rate and absorbed dose can be used to induce crosslinking and/or control the degree of crosslinking.
  • the temperature of the UHMWPE or mixture of UHMWPE and other components can be maintained below the melting point of the same. In some embodiments, during the irradiation, the temperature of the UHMWPE or mixture of UHMWPE and other components can be allowed to rise above the melting point of the same.
  • the temperature can be allowed to rise to, or the temperature can be maintained at, about 60 °C, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140, 145, 150, 155, 160, 165, 170, 175, 180, 185, 190, 195, 200, 210, 220, 230, 250, 275, or about 300 °C or more.
  • the UHMWPE or mixture of UHMWPE and other components can be preheated to a temperature below the melting point of the same, then subsequently irradiated while maintaining the temperature of the preheated UHMWPE or mixture of UHMWPE and other components below the melting point of the same.
  • the irradiating uses a total dose of about 1 kGy to about 100,000 kGy, 10 kGy to about 1000 kGy, about 50 kGy to about 500 kGy, 50 kGy to 300 kGy, or about 1 kGy or less, or about 5, 10, 15, 20, 25, 50, 75, 100, 125, 150, 175, 200, 250, 300, 350, 400, 500, 750, 1,000, 1,250, 1,500, 1,750, 2,000, 2,500, 3,000, 4,000, 5,000, 7,500, 10,000, 15,000, 20,000, 25,000, 50,000, 75,000, or about 100,000 kGy or more.
  • the irradiating includes using a dose rate of about 0.001 mGy/h to about 500 MGy/h, about 1 mGy/h to about 50 MGy/h, or about 0.001 mGy/h or less, or about 0.005 mGy/h, 0.01, 0.05, 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 22, 24, 26, 28, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 150, 200, 250, 300, 400, or about 500 MGy/h or more.
  • irradiative crosslinking can be performed in the presence of an additive that can promote or deter crosslinking, depending on the desired level of crosslinking.
  • Illustrative crosslinking promoters include, but are not limited to, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetraacrylate, and pentaerythritol tetramethacrylate.
  • the method can include post-irradiatively heating the irradiated solid material.
  • the post-irradiative heating is sufficient to melt at least part of the UHMWPE.
  • the post-irradiative heating provides a heated material.
  • the method can include solidifying the heated material, to provide a melt-stabilized material.
  • the post-irradiative heating can melt any suitable amount of the irradiated solid material, or of the UHMWPE in the irradiated solid material, such as about 1 vol% to about 100 vol%, or about 1 vol% or less, or about 2 vol%, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 96, 97, 98, or about 99 vol% or more.
  • the heating is sufficient to melt-stabilize the irradiated solid material, such that at least some of the free radicals (e.g., free radicals in the UHMWPE, which can be generated during irradiation) can recombine or otherwise be neutralized.
  • the method includes post-irradiatively heating the irradiated solid material in an environment including oxygen, the heating sufficient to melt at least part of the UHMWPE, to provide a heated material.
  • the method includes heating the irradiated solid material in an environment substantially free of oxygen.
  • Various embodiments of the present invention provide a means to reduce the oxidized layer that forms during melt-stabilization of a material including UHMWPE in an oxygen-containing environment such as air.
  • the antioxidant can scavenge the free radicals present in the outer layer that would normally be oxidized.
  • the heating can occur in an environment including any suitable amount of oxygen.
  • the heating can occur in an environment including ambient air, having about 20-21 vol% oxygen.
  • the heating can occur in an environment having about 1 vol% to about 50 vol% oxygen, about 10 vol% to about 30 vol% oxygen, about 1 vol% oxygen or less, or about 2 vol%, 3, 4, 5, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, or about 50 vol% oxygen or more.
  • the post-irradiative heating heats the irradiated solid material to any suitable temperature, such as about 50 °C to about 300 °C, about 80 °C to about 250 °C, about 130 °C to about 160 °C, about 50 °C or less, or about 60 °C, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 220, 240, 260, 280, or about 300 °C or more.
  • any suitable temperature such as about 50 °C to about 300 °C, about 80 °C to about 250 °C, about 130 °C to about 160 °C, about 50 °C or less, or about 60 °C, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 220, 240, 260, 280, or about 300 °C or more.
  • the irradiated solid material can be heated for any suitable duration, such as about 1 minute to about 7 days, or about 1 hour to about 48 hours, or about 1 minute or less, or about 2 minutes, 3, 4, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55 minutes, 1 hour, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23 hours, 1 day, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5 days, or about 7 days or more.
  • the solidifying can be any suitable solidifying, such that the melted material is allowed to solidify.
  • the solidifying can include allowing the post-irradiatively heated material to cool to a temperature below the melting point of the heated material, such as to room temperature.
  • the solidifying can occur in ambient conditions, or the solidifying can occur in a chilled environment.
  • the solidifying can occur in any medium, such as in a gas (e.g., air) or in a liquid (e.g., water).
  • the method can be effective to generate a melt-stabilized material including UHMWPE, melt-stabilized in an environment including oxygen, that has decreased or no oxidation in a surface layer of the material, as compared to other methods for melt-stabilization in an oxygen-containing environment.
  • the surface layer including decreased or no oxidation can be a surface layer that corresponds to the entire outer surface of the material, such as for a material including UHMWPE on the entire surface of the material (e.g., the material can be 100% UHMWPE or can have UHMWPE distributed evenly throughout).
  • the surface layer can be a portion of the outer surface that corresponds to a portion of the outer surface of the material, such as for a material including UHMWPE on only a portion of the surface of the material, or such as for a material that was only partially coated with the liquid composition including the antioxidant.
  • the surface layer can be a layer of any suitable depth as measured from the outside of the material, such as about 0 mm to about 1 mm deep, about 0 mm to about 10 mm deep, about 1 mm to about 10 mm deep, about 0 mm to about 20 mm deep, about 1 mm or less, or about 1.5 mm, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or about 20 mm deep or more.
  • the irradiated solid material can have a first concentration of free-radicals.
  • the first concentration of free-radicals can be any suitable concentration, such as about 1 ⁇ 10 15 spins/gram to about 1 ⁇ 10 20 spins/g, 1 ⁇ 10 16 spins/g to 1 ⁇ 10 18 spins/g, or about 1 ⁇ 10 15 spin/g or less, or about 1 ⁇ 10 16 spins/g, 1 ⁇ 10 17 , 1 ⁇ 10 18 , 1 ⁇ 10 19 , 1 ⁇ 10 20 , 1 ⁇ 10 21 , 1 ⁇ 10 22 , 1 ⁇ 10 23 , 1 ⁇ 10 24 , 1 ⁇ 10 25 , 1 ⁇ 10 26 , 1 ⁇ 10 27 , 1 ⁇ 10 28 , 1 ⁇ 10 29 , or about 1 ⁇ 10 30 spins/g or more.
  • the number of spins per gram of the material can be measured in any suitable fashion, such as by electron spin resonance (ESR).
  • the first concentration of free-radicals can be a concentration in the UHMWPE or a concentration in the irradiated solid including the UHMWPE.
  • the first concentration of free-radicals can be a concentration in a part or localized area of the material, or can be a concentration throughout the entire material including the UHMWPE.
  • the first concentration of free-radicals can be generated by and consistent with an amount of irradiation applied to the antioxidant-diffused solid material to crosslink the UHMWPE or to crosslink other components in the antioxidant-diffused solid material.
  • the method can include solidifying the post-irradiatively heated material, to provide a melt-stabilized material including UHMWPE including a second concentration of free-radicals, wherein the second concentration of free-radicals is less than the first concentration of free-radicals.
  • the melt-stabilization can reduce the concentration of free-radicals.
  • the concentration of free-radicals in the UHWMPE can be reduced.
  • the concentration of free-radicals in other materials can also optionally be reduced, for materials including other materials in addition to UHMWPE, such as other polyethylenes or other polymers.
  • the second concentration of free-radicals in the melt-stabilized material can be any suitable concentration that is lower than the first concentration of free radicals, such as about 1 ⁇ 10 5 spins/g to about 1 ⁇ 10 15 spins/g, or about 1 ⁇ 10 2 spins/g or less, or about 1 ⁇ 10 3 spins/g, 1 ⁇ 10 4 , 1 ⁇ 10 5 , 1 ⁇ 10 6 , 1 ⁇ 10 7 , 1 ⁇ 10 8 , 1 ⁇ 10 9 , 1 ⁇ 10 10 , 1 ⁇ 10 11 , 1 ⁇ 10 12 , 1 ⁇ 10 13 , 1 ⁇ 10 14 spins/g, 1 ⁇ 10 15 spins/g or more.
  • the number of spins per gram of the material can be measured in any suitable fashion, such as by electron spin resonance (ESR).
  • the second concentration of free-radicals can be a concentration in the UHMWPE or a concentration in all the materials the melt-stabilized material including the UHMWPE, corresponding to the part or localized area where the first concentration of free-radicals is determined.
  • the second concentration of free-radicals can be a concentration in a part or localized area of the material (e.g., corresponding to a part or localized area where the first concentration of free-radicals is measured), or can be a concentration throughout the melt-stabilized material including the UHMWPE.
  • the second concentration of free-radicals can be any suitable proportion of the first concentration of free-radicals.
  • the second concentration of free-radical s can be about 1% to about 0.000,1% of the first concentration of free-radicals, about 0.1% to about 0.001%, or about 1% or more, or about 0.5 %, 0.1, 0.05, 0.01, 0.005, 0.001, 0.000,5, or about 0.000,1% or less.
  • oxygen index refers to an area ratio of fourier transform infrared (FTIR) peaks at 1765-1680 cm -1 (e.g. carbonyl peaks) to FTIR peaks 1392-1330 cm -1 (e.g., methyl peaks), wherein the area of the carbonyl absorptions centered near 1720 cm -1 is related to the amount of chemically bound oxygen present in the material, and the intensity (area) of the C-H absorption centered near 1370 cm -1 is used to normalize for the sample's thickness.
  • FTIR Fourier transform infrared
  • a surface layer (e.g., the entire surface, or only part of the surface, of any suitable depth) of the melt-stabilized material can have an oxidation index that does not exceed 1 (e.g., the average oxidation index of the surface layer does not exceed an oxidation index of 1 or any portion of the surface layer does not exceed an oxidation index of 1).
  • the surface layer of the melt-stabilized material has an oxidation index that does not exceed 0.5, or that is about 0.001 to about 1, 0.01 to about 0.5, or about 0.001 or less, or that is equal to or less than about 0.002, 0.003, 0.004, 0.005,0.006, 0.008, 0.01, 0.015, 0.02, 0.025, 0.03, 0.035, 0.04, 0.045, 0.05, 0.055, 0.06, 0.065, 0.07, 0.075, 0.08, 0.085, 0.09, 0.095, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.6, 0.7, 0.8, 0.9, or about 1 or more.
  • the surface layer can be a layer of any suitable depth on the material, such as about 0 mm deep (e.g., the top surface most exposed to oxygen), or a layer about 0 mm deep to about 1 mm deep, about 0 mm deep to about 10 mm deep, or about 1 mm deep or less, or about 2 mm, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or about 20 mm deep or more.
  • about 0 mm deep e.g., the top surface most exposed to oxygen
  • the melt-stabilized material can have any suitable concentration of antioxidant at various depths from the surface of the material.
  • the coating, pre-irradiative heating, irradiating, and melt-stabilizing can be sufficient such that the melt-stabilized material has a vitamin E index (VEI, the FTIR ratio of the peak areas between 1275 and 1245 cm -1 to the peak areas between 1985 and 1850 cm -1 ) in a surface layer of about -0.1 to about 0.5, about -0.05 to about 0.25, about 0.01 to about 0.25, about 0.05 to about 0.25, about 0.1 to about 0.25, or about -0.1 or less, or about -0.08, -0.06, - 0.04, -0.02, -0.01, 0, 0.01, 0.02, 0.04, 0.06, 0.08, 0.1, 0.12, 0.14, 0.16, 0.18, 0.2, 0.22, 0.24, 0.26, 0.28, 0.3, 0.35, 0.4, 0.45
  • the surface layer can be a layer of any suitable depth on the material, such as about 0 mm deep (e.g., the top surface most exposed to oxygen), or a layer about 0 mm deep to about 1 mm deep, about 0 mm deep to about 10 mm deep, or about 1 mm deep or less, or about 2 mm, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or about 20 mm deep or more.
  • the VEI can be a gradient that is highest at a depth of 0 mm and that becomes lower at deeper depths.
  • the VEI can be substantially similar throughout the surface layer or throughout the melt-stabilized material.
  • the melt-stabilized material can have any suitable concentration of the coated and diffused antioxidant at various depths from the surface of the material, such as an antioxidant (e.g., vitamin E), or such as another component.
  • an antioxidant e.g., vitamin E
  • the coating, pre-irradiative heating, irradiating, and melt-stabilizing can be sufficient such that the melt-stabilized material has a concentration of an antioxidant such as vitamin E in a surface layer of about 0.001 wt% to about 10 wt%, about 0.01 wt% to about 5 wt%, about 0.1 wt% to about 2.5 wt%, about 0.1 wt% to about 1 wt%, or about 0.001 wt% or less, or about 0.01, 0.1, 0.2, 0.4, 0.6, 0.8, 1, 1.2, 1.4, 1.6, 1.8, 2, 2.4, 2.6, 2.8, 3, 3.5, 4, 4.5, 5, 6, 7, 8, 9, or about 10 wt% or
  • the surface layer can be a layer of any suitable depth on the material, such as about 0 mm deep (e.g., the top surface most exposed to oxygen), or a layer about 0 mm deep to about 1 mm deep, about 0 mm deep to about 10 mm deep, or about 1 mm deep or less, or about 2 mm, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or about 20 mm deep or more.
  • the concentration of the antioxidant can be a gradient (linear or non-linear) that is highest at a depth of 0 mm and that becomes lower at deeper depths.
  • the concentration of the component can be substantially similar throughout the surface layer or throughout the melt-stabilized material.
  • UHMWPE material and medical implant including the same.
  • the present invention provides a melt-stabilized material made by any suitable embodiment of a method described herein.
  • the present invention provides an oxygen-containing-environment-melt-stabilized material including UHMWPE and an antioxidant, the antioxidant introduced prior to an irradiation step, the melt-stabilized material being free of post-melt-stabilization oxidized surface layer removal greater than about 1 mm depth, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, or greater than about 10 mm depth, wherein the UHMWPE in a surface layer (e.g., about 0 mm deep, or a layer about 0 mm deep to about 1 mm deep, about 0 mm deep to about 10 mm deep, or about 1 mm deep or less, or about 2 mm, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or about 20 mm deep or more) of the melt-stabilized material (e.
  • the present invention provides a medical implant including any suitable melt-stabilized material including UHMWPE that can be produced by an embodiment of the method described herein.
  • the method of melt-stabilizing UHMWPE can include generating a medical implant from the resulting material, such that the method is a method of making a medical implant.
  • various amounts of the surface of the melt-stabilized material can be removed during processing and machining the material into the desired shape for the implant, such as about 0 mm to about 1 mm, about 0 mm to about 5 mm, about 0 mm to about 10 mm, about 0.1 mm or less, or about 0.5 mm, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or about 20 mm or more.
  • the medical implant can be an orthopedic implant.
  • the medical implant can form or be part of an artificial hip, hip liner, knee, knee liner, disk replacement, shoulder, elbow, foot, ankle, finger, mandible, or bearings in an artificial heart.
  • Oxidation levels were determined through the blocks at center from top to bottom and side to side of each block, bottom denoting the surface the block was setting on during the melt stabilization process.
  • the FTIR Oxidation Index (OI) was determined per ASTM F2102-06. Following the ASTM F2102-06 protocol, 100-200 micron thick films were microtomed from the block of material, with the top indicative of the initial incident irradiation face. The film was scanned with an FTIR spectrophotometer using an indexing microscopic attachment to obtain infrared spectra at 200 micron intervals across the entire length of the film.
  • the oxidation index at various locations scanned was then calculated using the ratio of the oxidation peak (1765-1680 cm -1 , centered at 1720 cm -1 ) to a control peak that does not change with irradiation (1392-1330 cm -1 , centered at 1370 cm -1 ).
  • the trans-vinylene index throughout the Examples is determined as the area of the infrared absorption peak centered near 965 cm -1 to the area of the of the C-H absorption peak centered near 1370 cm -1 .
  • Polymer main chain unsaturation in the form of trans-vinyl groups are a side reaction during crosslinking via ionizing radiation such as gamma, x-ray and electron beam.
  • the correlation between TVI and actual received radiation dose can depend on the nature of the irradiation conditions, for example, radiation source (gamma or electron beam), temperature, dose rate, and oxygen level.
  • the amount of unsaturation formation can be directly correlated with the amount of irradiation (e.g., dose), and can be used as a dosimeter for a given material and irradiation method combination.
  • the vitamin E-phosphite was synthesized as follows.
  • the equipment used included (1) three neck schlenk style round bottom 100 ml flask; (1) gas inlet, schlenk; (1) addition funnel, schlenk; (1) reflux condenser, schlenk; (1) filter funnel, 25-50 ⁇ m glass frit disc, schlenk; (1) single neck collection flask, 100 ml, schlenk; (1) distillation adapter, schlenk; (1) water chilled condenser, schlenk; (1) single neck collection flask, 50 ml, schlenk; (1) magnetic stir bar to fit 100 ml round bottom flask; (1) pipet, 5 ml; (1) pipet, 1 ml; (1) pipet bulb; (1) lab scale, resolution ⁇ 0.001 g; (1) hot plate with magnetic stir capability; and (1) glass jar with large stir bar for use as heating bath.
  • the materials also included all racemic d,l- ⁇ -tocopherol; HPLC grade dichloromethane; triethylamine, assay ⁇ 99%; Aldrich grade reagent-plus PCl 3 . assay ⁇ 99%; molecular sieves, type 3A, 8-12 mesh; dry nitrogen gas; and heat transfer oil.
  • Activated molecular sieves, type 3A, 8-12 mesh were dried 4 hours @ 220 C, cooled 1 hour @ 110 C, and returned to dried glass container.
  • Fisher HPLC grade dichloromethane and Sigma-Aldrich triethylamine, assay ⁇ 99% were dried over activated molecular sieves prior to use.
  • the reaction flask was slowly heated with stirring to 60 °C with a reflux condenser attached to the flask maintaining the dry nitrogen purge and maintain for one hour at 60 °C.
  • Precipitate was filtered off using dry nitrogen purge/vacuum with 25-50 ⁇ m glass frit disc filter, and 100 ml collection flask, Schlenk.
  • the single neck 100 ml collection flask used to collect the product was fitted with a distillation adapter, water chilled condenser, vacuum adapter and 50 ml collection flask. To remove volatiles, the 100 ml collection flask was heated to 100 °C overnight under dry nitrogen purge with stirring, then a vacuum was applied for one hour maintaining the 100 °C temperature with stirring.
  • the remaining product was hot filtered using dry nitrogen purge/vacuum with 25-50 ⁇ m glass frit disc filter, and 100 ml tared collection flask, Schlenk. The filtrate was cooled to ambient under dry nitrogen purge. The product weight was 7.1 g (clear, amber liquid).
  • the product was diluted quantitatively to a 10% by weight solution in dry dichloromethane. The diluted product was stored under dry nitrogen in a sealed glass container, in a dessicator. Remaining VE-Phosphite in glassware was recovered, after sitting several weeks in air and light, by dilution with dry dicholormethane and subsequent filtering. The recovered product weight was 6.3 g (clear, amber liquid).
  • the recovered VEP was obtained by a secondary cleaning of the glassware used for synthesis of the VEP, which had some increased exposure to oxygen during recovery as compared to the VEP which was maintained under an inert environment until application to the UHMWPE section.
  • Table 1 illustrates oxidation index to a depth of 5 mm as measured from the top, bottom, and both sides of Samples 1.1.1-1.1.4.
  • Table 1. Oxidation index for Samples 1.1.1-1.1.4. Sample Dept h, ⁇ Top OI Btm OI Side 1 OI Side 2 OI Top TVI Btm TVI Side 1 TVI Side 2 TVI AO Treatment 1.1.1 0 5.343 0.305 6.224 7.026 0.037 0.015 0.057 0.049 None 200 1.736 0.214 3.039 2.588 0.026 0.025 0.026 0.025 400 0.551 0.140 0.880 0.717 0.031 0.017 0.026 0.039 600 0.294 0.128 0.358 0.210 0.034 0.014 0.028 0.048 800 0.151 0.128 0.149 0.124 0.036 0.013 0.031 0.048 1000 0.117 0.115 0.117 0.110 0.034 0.014 0.033 0.048 1200 0.118 0.105 0.114 0.102 0.036 0.015
  • the recovered VEP was obtained by a secondary cleaning of the glassware used for synthesis of the VEP, which had some increased exposure to oxygen during recovery as compared to the VEP which was maintained under an inert environment until application to the UHMWPE section.
  • Table 2 illustrates oxidation index to a depth of 5 mm as measured from the top, bottom, and both sides of Samples 2.1.1-2.1.4. Table 2.
  • the recovered VEP was obtained by a secondary cleaning of the glassware used for synthesis of the VEP, which had some increased exposure to oxygen during recovery as compared to the VEP which was maintained under an inert environment until application to the UHMWPE section.
  • Table 3 illustrates oxidation index to a depth of 5 mm as measured from the top, bottom, and both sides of Samples 3.1.1-3.1.4.
  • the recovered VEP was obtained by a secondary cleaning of the glassware used for synthesis of the VEP, which had some increased exposure to oxygen during recovery as compared to the VEP which was maintained under an inert environment until application to the UHMWPE section.
  • Table 4 illustrates oxidation index to a depth of 5 mm as measured from the top, bottom, and both sides of Samples 4.1.1-4.1.4. Table 4. Oxidation index for Samples 4.1.1-4.1.4. Sample Depth, ⁇ Top OI Btm OI Side 1 OI Side 2 OI Top TVI Btm TVI Side 1 TVI Side 2 TVI AO Treatment 4.1.1 0 4.065 1.585 4.438 5.816 0.064 0.023 0.054 0.054 None 200 2.891 0.806 3.125 2.755 0.023 0.016 0.026 0.022 400 0.863 0.551 1.150 0.885 0.025 0.014 0.023 0.024 600 0.346 0.496 0.482 0.438 0.029 0.011 0.026 0.028 800 0.136 0.235 0.257 0.207 0.032 0.010 0.029 0.029 1000 0.082 0.154 0.154 0.127 0.032 0.009 0.030 0.029 1200 0.047 0.098 0.130 0.106 0.0
  • the recovered VEP was obtained by a secondary cleaning of the glassware used for synthesis of the VEP, which had some increased exposure to oxygen during recovery as compared to the VEP which was maintained under an inert environment until application to the UHMWPE section.
  • Table 5 illustrates oxidation index to a depth of 5 mm as measured from the top, bottom, and both sides of Samples 5.1.1-5.1.4. Table 5. Oxidation index for Samples 5.1.1-5.1.4. Sample Depth, ⁇ Top OI Btm OI Side 1 OI Side 2 OI Top TVI Btm TVI Side 1 TVI Side 2 TVI AO Treatment 5.1.1 0 8.399 4.524 9.204 7.441 0.047 0.043 0.047 0.049 None 200 3.758 2.601 3.853 5.347 0.032 0.034 0.035 0.040 400 1.027 1.207 1.090 1.632 0.033 0.035 0.035 0.042 600 0.512 0.624 0.547 0.789 0.034 0.037 0.036 0.046 800 0.313 0.36:s 0.331 0.496 0.034 0.036 0.036 0.046 1000 0.318 0.236 0.331 0.293 0.037 0.036 0.046 1200 0.276 0.172 0.303
  • the recovered VEP was obtained by a secondary cleaning of the glassware used for synthesis of the VEP, which had some increased exposure to oxygen during recovery as compared to the VEP which was maintained under an inert environment until application to the UHMWPE section.
  • Table 6 illustrates oxidation index to a depth of 5 mm as measured from the top, bottom, and both sides of Samples 6.1.1-6.1.4. Table 6. Oxidation index for Samples 6.1.1-6.1.4. Sample Depth, A Top OI Btm OI Side 1 OI Side 2 OI Top TVI Btm TVI Side 1 TVI Side 2 TVI AO Treatment 6.1.1 0 5.614 4.718 2.477 0.769 0.037 0.063 0.097 0.037 None 200 1.277 2.597 2.026 0.365 0.020 0.026 0.035 0.035 400 0.531 0.847 0.747 0.159 0.029 0.029 0.038 0.039 600 0.201 0.377 0.331 0.112 0.036 0.035 0.043 0.039 800 0.162 0.150 0.163 0.095 0.037 0.039 0.047 0.039 1000 0.118 0.097 0.113 0.083 0.036 0.039 0.046 0.039 1200 0.127 0.082 0.090 0.078
  • Table 7 illustrates average oxidation index and average trans vinyl index, along with standard deviations, for all of the samples in Examples 1-6. Table 7. Average oxidation index and average trans vinyl index for Example 1-6, where "TB" indicates top to bottom, and where "SS" indicates side to side.

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Claims (13)

  1. Procédé de stabilisation à l'état fondu d'un polyéthylène à ultra haut poids moléculaire (PEUHPM), le procédé comprenant :
    l'enduction d'un matériau consolidé solide comprenant un PEUHPM avec un antioxydant, de sorte que l'antioxydant ne pénètre pas au-delà d'une profondeur de 0 mm de la surface d'application, de manière à fournir un matériau solide enduit d'antioxydant ;
    le préchauffage par irradiation du matériau solide enduit d'antioxydant pour diffuser l'antioxydant en son sein, de manière à fournir un matériau solide ayant subi une diffusion d'antioxydant ;
    l'irradiation du matériau solide ayant subi une diffusion d'antioxydant avec un faisceau d'électrons, de manière à fournir un matériau solide irradié ;
    l'après-chauffage par irradiation du matériau solide irradié dans un environnement contenant de l'oxygène pour fondre au moins une partie du PEUHPM, de manière à fournir un matériau chauffé ; et
    la solidification du matériau chauffé, de manière à fournir un matériau stabilisé à l'état fondu.
  2. Procédé selon la revendication 1, ladite diffusion de l'antioxydant dans le matériau solide enduit d'antioxydant permettant la pénétration de l'antioxydant jusqu'à une profondeur d'au moins 1 mm de la surface du matériau solide ayant subi une diffusion d'antioxydant.
  3. Procédé selon la revendication 1, comprenant le refroidissement du matériau solide ayant subi une diffusion d'antioxydant avant l'irradiation.
  4. Procédé selon la revendication 1, ledit préchauffage par irradiation comprenant le chauffage jusqu'à fondre d'au moins une partie du PEUHPM.
  5. Procédé selon la revendication 1, ledit préchauffage par irradiation comprenant le préchauffage jusqu'à une température supérieure ou égale à une température de préchauffage de manière à fournir un matériau solide ayant subi une diffusion d'antioxydant préchauffé, ladite irradiation du matériau solide ayant subi une diffusion d'antioxydant comprenant l'irradiation du matériau solide ayant subi une diffusion d'antioxydant préchauffé.
  6. Procédé selon la revendication 1, après ledit préchauffage par irradiation, comprenant en outre le préchauffage du matériau solide ayant subi une diffusion d'antioxydant jusqu'à une température supérieure ou égale à une température de préchauffage de manière à fournir un matériau solide ayant subi une diffusion d'antioxydant préchauffé, ladite irradiation du matériau solide ayant subi une diffusion d'antioxydant comprenant l'irradiation du matériau solide ayant subi une diffusion d'antioxydant préchauffé.
  7. Procédé selon la revendication 1, ladite irradiation comprenant l'irradiation avec un débit de dose de 0,001 mGy/h à 500 MGy/h.
  8. Procédé selon la revendication 1, ledit antioxydant étant au moins l'un parmi un tocophérol, un phosphite de tocophérol, un tocotriénol, la vitamine E, l'acétate de vitamine E, une vitamine E protégée, une huile de romarin, le pentaérythritol tétrakis(3-(3,5-di-tert-butyl-4-hydroxyphényl)propionate), le copolymère ester de diméthyle de l'acide butanedioïque/4-hydroxy-2,2,6,6-tétraméthyl-1-pipéridine éthanol, l'acide tannique, un extrait de myrtille, la vitamine C, un carotène, un flavonoïde, un isoflavonoïde, un néoflavonoïde, une lignine, la quinine, l'ubiquinone, la vitamine K1, un métal, le glutathion, le gallate de propyle, le gallate d'octyle, le gallate de lauryle, le resvératrol, l'acide rosmarinique, la rutine, l'acide 5-aminosalicylique, l'hydroxyanisole butylé, l'hydroxytoluène butylé, un composé phénolique, et un stabilisant d'amine monomère ou polymère encombrée.
  9. Procédé selon la revendication 1, ledit antioxydant étant un stabilisant d'amine encombrée ou un stabilisant de phénol encombré.
  10. Procédé selon la revendication 9, ledit antioxydant étant un stabilisant d'amine encombrée et ledit stabilisant d'amine encombrée étant au moins l'un parmi un diester de 2,2,6,6-tétra((C1-C50)hydrocarbyl)-4-pipéridyle de HOC(O)-(C1-C50)hydrocarbyl-C(O)OH, un diester de 2,2,6,6-tétraméthyl-4-pipéridyle de HOC(O)-(C1-C50)hydrocarbyl-C(O)OH, le sébacate de bis(2,2,6,6-tétraméthyl-4-pipéridyle), un diester de 1,2,2,6,6-penta((C1-C50)hydrocarbyl)-4-pipéridyle de HOC(O)-(C1-C50)hydrocarbyl-C(O)OH, un diester de l,2,2,6,6-pentaméthyl-4-pipéridyle de HOC(O)-(C1-C50)hydrocarbyl-C(O)OH, la 2,2,6,6-tétraméthylpipéridine, chaque groupe (C1-Cso)hydrocarbyle étant indépendamment choisi, étant substitué ou non substitué, et étant interrompu par 0, 1, 2 ou 3 groupes -O-.
  11. Procédé selon la revendication 1, ledit antioxydant étant un tocophérol or tocotriénol protégé comportant la structure :
    Figure imgb0053
     ou un sel de celui-ci, ou
    Figure imgb0054
     ou un sel de celui-ci,
    dans laquelle
    à chaque occurrence, Ra est indépendamment choisi parmi les groupes -H, -E et (C1-C10)hydrocarbyle substitué ou non substitué,
    E comporte la structure :
    Figure imgb0055
     ou
    Figure imgb0056
     et
    R7, R8, et R9 sont chacun indépendamment choisis parmi les groupes -H, (C1-C10)alkyle substitué ou non substitué, et (C1-C10)alcényle substitué ou non substitué.
  12. Procédé selon la revendication 1, ledit antioxydant étant un tocophérol ou tocotriénol protégé par stabilisant d'amine encombrée de formule (I) :
    Figure imgb0057
    ou un sel de celui-ci ;
    dans laquelle
    R1, R2, R3 et R4 représentent chacun, indépendamment, un atome d'hydrogène ou un groupe (C1-C10)alkyle,
    R5 est choisi parmi un atome d'hydrogène, les groupes (C1-C10)alkyle,-O· et -OR11 dans lequel R11 représente un atome d'hydrogène ou un groupe (C1-C10)alkyle,
    E comporte la structure :
    Figure imgb0058
    Figure imgb0059
    dans laquelle R7, R8 et R9 sont chacun indépendamment choisis parmi les groupes -H, (C1-C10)alkyle substitué ou non substitué, et (C1-C10)alcényle substitué ou non substitué, et
    Y représente le groupe :
    Figure imgb0060
    dans lequel R6 représente un atome d'hydrogène, un groupe (C1-C10)alkyle,-E, ou un radical de la formule :
    Figure imgb0061
  13. Procédé de stabilisation à l'état fondu d'un polyéthylène à ultra haut poids moléculaire (PEUHPM), le procédé comprenant :
    l'enduction d'un matériau consolidé solide comprenant un PEUHPM avec un antioxydant de vitamine E protégée de sorte que l'antioxydant ne pénètre pas au-delà d'une profondeur de 0 mm de la surface d'application, de manière à fournir un matériau solide enduit d'antioxydant, ledit antioxydant de vitamine E protégée étant au moins l'un parmi au moins un tocophérol ou tocotriénol protégé comportant la structure :
    Figure imgb0062
     ou un sel de celui-ci, ou
    Figure imgb0063
     ou un sel de celui-ci,
    dans laquelle
    à chaque occurrence, Ra est indépendamment choisi parmi les groupes -H, -E et (C1-C10)hydrocarbyle substitué ou non substitué,
    E comporte la structure :
    Figure imgb0064
     ou
    Figure imgb0065
     et
    R7, R8 et R9 sont chacun indépendamment choisis parmi les groupes -H, (C1-C10)alkyle substitué ou non substitué, et (C1-C10)alcényle substitué ou non substitué, et
    un tocophérol ou tocotriénol protégé par stabilisant d'amine encombrée de formule (I) :
    Figure imgb0066
    ou un sel de celui-ci ;
    dans laquelle
    R1, R2, R3 et R4 représentent chacun, indépendamment, un atome d'hydrogène ou un groupe (C1-C10)alkyle,
    R5 est choisi parmi un atome d'hydrogène, les groupes (C1-C10)alkyle,-O· et -OR11 dans lequel R11 représente un atome d'hydrogène ou un groupe (C1-C10)alkyle,et
    Y représente le groupe :
    Figure imgb0067
    dans lequel R6 représente un atome d'hydrogène, un groupe (C1-C10)alkyle,-E, ou un radical de la formule :
    Figure imgb0068
    le préchauffage par irradiation du matériau solide enduit d'antioxydant pour diffuser l'antioxydant en son sein, de manière à fournir un matériau solide ayant subi une diffusion d'antioxydant ;
    l'irradiation du matériau solide ayant subi une diffusion d'antioxydant avec un faisceau d'électrons, de manière à fournir un matériau solide irradié ;
    l'après-chauffage par irradiation du matériau solide irradié dans un environnement contenant de l'oxygène pour fondre au moins une partie du PEUHPM, de manière à fournir un matériau chauffé ; et
    la solidification du matériau chauffé, de manière à fournir un matériau stabilisé à l'état fondu.
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EP3170515A1 (fr) 2005-08-18 2017-05-24 Zimmer GmbH Articles de polyéthylène à poids moléculaire très élevé et procédés de formation d'articles de polyéthylène à poids moléculaire très élevé
US8664290B2 (en) 2007-04-10 2014-03-04 Zimmer, Inc. Antioxidant stabilized crosslinked ultra-high molecular weight polyethylene for medical device applications
WO2015138137A1 (fr) 2014-03-12 2015-09-17 Zimmer, Inc. Polyéthylène à poids moléculaire ultra-élevé stabilisé à l'état fondu et son procédé de fabrication
CA2969751C (fr) 2014-12-03 2020-09-22 Zimmer, Inc. Preparation d'un polyethylene de poids moleculaire tres eleve impregne d'antioxydant
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WO2020003048A1 (fr) * 2018-06-25 2020-01-02 Songwon Industrial Co., Ltd. Stabilisateurs de polyoléfines à fragmentation réduite
CN111073004B (zh) * 2019-12-16 2022-11-01 四川大学 提高超高分子量聚乙烯关节材料辐照交联密度和氧化稳定性的方法
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Citations (1)

* Cited by examiner, † Cited by third party
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WO2016090084A1 (fr) * 2014-12-03 2016-06-09 Zimmer, Inc. Préparation d'un polyéthylène de poids moléculaire très élevé imprégné d'antioxydant

Family Cites Families (13)

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Publication number Priority date Publication date Assignee Title
ATE300964T1 (de) * 1996-02-13 2005-08-15 Massachusetts Inst Technology Bestrahlte und schmeltzbehandelte ultrahoch molekulare polyethylen prothesen
WO1998016258A1 (fr) * 1996-10-15 1998-04-23 The Orthopaedic Hospital Polyethylene reticule a gradient de surface, resistant a l'usure
JP5122126B2 (ja) * 2003-01-16 2013-01-16 ザ・ジェネラル・ホスピタル・コーポレイション 耐酸化性ポリマー物質の製造方法
AU2005209868B8 (en) * 2004-02-03 2010-06-03 The General Hospital Corporation Dba Massachusetts General Hospital Highly crystalline cross-linked oxidation-resistant polyethylene
US7803310B2 (en) * 2005-06-14 2010-09-28 Omni Life Science, Inc. Crosslinked polyethylene article
US9441081B2 (en) * 2007-03-02 2016-09-13 The General Hospital Corp. Cross-linking of antioxidant-containing polymers
EP2486948B1 (fr) * 2007-04-10 2018-02-21 Zimmer, Inc. Polyéthylène antioxydant, réticulé, stabilisé, à poids moléculaire très élevé pour des applications de dispositifs médicaux
ATE529475T1 (de) * 2007-11-06 2011-11-15 Dsm Ip Assets Bv Verfahren zur herstellung von polyethylen mit ultrahohem molekulargewicht
BRPI0822692A2 (pt) * 2008-05-13 2015-07-07 Smith & Nephew Orthopaedics Ag Uhmwpe altamente reticulado resistente a oxidação
WO2010096771A2 (fr) * 2009-02-20 2010-08-26 The General Hospital Corporation Dba Fusion à température élevée
US8399535B2 (en) * 2010-06-10 2013-03-19 Zimmer, Inc. Polymer [[s]] compositions including an antioxidant
US20140024736A1 (en) * 2010-11-03 2014-01-23 Zimmer, Inc. Polymer articles having chemically bonded agents and methods of making the same
US10000305B2 (en) * 2012-05-11 2018-06-19 The General Hospital Corporation Antioxidant-stabilized joint implants

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2016090084A1 (fr) * 2014-12-03 2016-06-09 Zimmer, Inc. Préparation d'un polyéthylène de poids moléculaire très élevé imprégné d'antioxydant
EP3227360A1 (fr) * 2014-12-03 2017-10-11 Zimmer, Inc. Préparation d'un polyéthylène de poids moléculaire très élevé imprégné d'antioxydant

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CN107667137A (zh) 2018-02-06
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US20160280863A1 (en) 2016-09-29
WO2016153925A1 (fr) 2016-09-29

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